Installing a new sprinkler controller system. Please help me wire it!

I'm swapping out sprinkler controller boxes and I'm a bit confused of the "C" common and power source. Please someone email me there email address and I will send you 2 clear pics ofthe currant wireing and the new box. Please tell me what to hook up to what.
SOMEONEHELP. THANKS
MY EMAIL ADDRESS IS GGABBARA@aol.com